/*******************************************************************************
 * Copyright 2011 Mauro Luigi Drago (drago.luigi@gmail.com)
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *******************************************************************************/
package com.bytenose.extrautils.concurrent;

import com.bytenose.extrautils.annotations.ThreadSafe;

/**
 * <p>A source of cancellation tokens to signal and propagate cancellation
 * requests when executing asynchronous operations.</p>
 * 
 * <p>All the methods of this class are thread safe and may be used concurrently</p>
 * 
 * <p>The interface of this class is inspired (and copied for some of its parts) 
 * from the Microsoft .NET 4 platform.</p>
 * 
 * @author Mauro Luigi Drago
 *
 */
@ThreadSafe
public final class CancellationTokenSource {

	/** The cancellation token associated to this source */
	private final CancellationToken token = new CancellationToken();
	
	/**
	 * Creates a new {@link CancellationTokenSource}.
	 */
	public CancellationTokenSource() {
	}
	
	/**
	 * Communicates a request of cancellation to the tokens associated
	 * to this source. 
	 * This method has no effect if cancellation has been already requested.
	 */
	public void cancel() {
		token.cancel();
	}
	
	/**
	 * Gets the cancellation token associated to this source.
	 * @return the cancellation token.
	 */
	public CancellationToken getToken() {
		return token;
	}
}
